The TARDIS lands on a planet that is about to explode.  There are only two other spaceships on the planet.  One belongs to the Rills who use robots to perform recon missions for them and another to the Drahvins, a group of beautiful women.  The Rills spaceship will be repaired before the catastrophe but the Drahvins' will not.  The Drahvins force the Doctor and Vicki into attempting to take over the Rills ship by holding Steven hostage.